Cats have a natural instinct to protect their territory from intruders. This behavior is typical in most animal species, and is often stronger in hunting species as compared to prey species. Cats, of course, are natural hunters. They instinctively protect their territory to ensure that they, and their offspring, will have ready access to resources such as food, water and shelter. This instinct is referred to as territorial aggression.
Territorial aggression can be displayed in many ways, most often when a new cat is brought into an existing cat household. The cat whose home is being “invaded” (by the addition of a new cat) may have a very mild reaction, a very strong reaction, or have a reaction somewhere in-between.
A mild reaction or display of territorial aggression might not include any hissing or scratching, but instead, the cat may simply take the highest available position near his food and water bowls. This is a very subtle display of dominance (I am higher than you are; I have the upper hand; I can easily leap down upon you, the intruder cat, if you even attempt to come near my food and water), with the potential to quickly escalate to overt aggression. The new cat recognizes the implied threat. To avoid engaging in a fight, the new cat may wait for the original cat to eat his fill at the food bowl before approaching for the leftovers.
A slightly less mild display of territorial aggression in your cat might include some posturing in front of the new cat, sometimes with flattened ears, arched back, hissing and some swatting (usually with claws kept in) whenever the new cat comes near the original cat or the original cat’s prime spots for eating, drinking and sleeping. These displays tend to be short-lived; as soon as the new cat moves away from the original cat, the original cat settles down.
A strong reaction and display of territorial aggression may include all of the elements from a relatively mild display – that is, flattening of ear, hissing and some swatting – but a strong reaction goes further. The original cat may stalk the new cat, so that no matter where the new cat goes, the original cat treats it as unacceptable. The original cat chases the new cat, tackling, growling, scratching and biting. The claws, as they say, come out; at this level, a territorially aggressive cat is likely to inflict some damage to the intruder cat.
Territorial aggression between cats often is self-limiting. The new cat often will display some signs of submissive behavior to the original cat, and over time, the two cats adjust to being kept in the same household, as they determine who is more dominant than the other. Unfortunately, territorial aggression from a cat is not limited to a new cat being brought into a household.
Territorial aggression can be directed to any other living creature, even visiting human guests. I have personally witnessed cats taking the highest available positions (such as the top of a refrigerator in a kitchen), ready to pounce on an unsuspecting human visitor as they pass by. Cats are masters of hiding before an attack as well, so low spots that are difficult for humans to clearly see often act as a pre-attack sanctuary for territorially aggressive cats. A low couch, or even a chair tucked under a kitchen table, provide hidden spots from which a cat can quickly rush out as “the intruder” passes by. This is the behavior that should come to mind when one says “Attack cat lives here”.
While it might seem cute when a little kitten displays some degree of territorial aggression, the behaviors of territorial aggression lose the cuteness-factor as the cat becomes a full-grown predator, with claws designed to slice through fur and skin. For infants and small children, being targeted by an overly aggressive “attack cat” is no laughing matter. Very young infants have no protection from a territorially aggressive cat, and while toddlers and young children might be better able to raise up their hands to defend themselves than an infant, a territorially aggressive cat can pose a significant risk to a youngster. Experienced cat owners know to discourage territorial aggressive posturing from their cats.